Drag lines for concrete

ABSTRACT

An automatic dragline is disclosed including a hollow tower which supports a motor driven rotating platform from which a cantilever jib extends for supporting a dragline bucket positionable for use in bunkers defined by radial walls extending from the tower with selectively operable ports in the bottom of the tower in each bunker enabling material feed from each bunker to the tower interior; material detectors are located at the maximum material level on the tower wall in each bunker; an automatic control circuit including bucket height detectors, cable slack detectors and winch control members insures optimum movement efficiency of the dragline bucket.

Vidal DRAG LINES FOR CONCRETE [76] Inventor: Lucien Ren Vidal, Domaine de la Pimpine, 33360 Latresne, France [22] Filed: May 22, 1973 [21] Appl. No.: 363,170

[30] Foreign Application Priority Data May 23, 1972 France .1 72.18370 [52] U.S. Cl. 198/36, 214/10 [51] Int. Cl.. 1. B65g 65/28 [58] Field of Search 214/10, 17 DB, 16 R; 198/36; 37/115, 116, 117; 172/265, 26.6

[56] References Cited UNITED STATES PATENTS 3,460,278 8/1969 Pesavento et al 37/116 3,488,036 l/l970 Feger et al 37/116 X 3,495,723 2/1970 Reymann et al... 214/10 3,556,317 l/l97l Vidal 214/10 Dec. 3, 1974 Lawrence [5 7] ABSTRACT An automatic dragline is disclosed including a hollow tower which supports a motor driven rotating platform from which a cantilever jib extends for supporting a dragline bucket positionable for use in bunkers defined by radial walls extending from the tower with selectively operable ports in the bottom of the tower in each bunker enabling material feed from each bunker to the tower interior; material detectors are located atthe maximum material level on the tower wall in each bunker; an automatic control circuit including bucket height detectors, cable slack detectors and winch control members insures optimum movement efficiency of the dragline bucket.

9 Claims, 13 Drawing Figures PATENIEL DEB 3mm SHEET 1 OF 7 DRAG LINES FOR CONCRETE The present invention relates to an automobile dragline for feeding various materials (sand, fine gravels, pebbles, etc.) to a concrete production station.

Certain known draglines include a tower forming part of radial walls separating bunkers for the storage of materials tipped in bulk into their inlets and provided at its base with hoods for distributing these materials to the station. The tower supports a rotating platform which can be rotated by a motor and reduction gear unit. A jib is mounted in cantilever on the platform over the bunkers; it supports a return cable wound on a first winch and fastened to the back of a bucket, the

front of which is linked to a scraping cable wound on a second winch; this bucket travels in the bunkers in accordance with a particular cycle, exclusively as a result of the action of the scraping winch and the return winch which are carried by the rotating platform.

These known draglines are not entirely automatic, and this necessitates the permanent presence of a driver.

Moreover, even for certain other more complex draglines, in which partial automation has been achieved, the inoperative periods are too long relative to the true duration of active work. This results in the provision of an excessively large dragline storage capacity, relative to the throughput of the concrete station.

Furthermore, these known draglines have no operational flexibility, in that they are not adaptable to the conditions of use, which can lead to additional work in the overloaded bunkers and the temporary neglect of the others.

Finally, from the point of view of safety, they require human surveillance, for it is impossible to automatically avoid certain unforseeable hazards.

The present invention is intended to correct these disadvantages, by making the dragline entirely automatic, intelligent in respect of the decision which it makes at each moment between several operational possibilities, extremely active due to a considerable reduction in inoperative periods and extremely safe due to automatic stoppage when a functional anomaly appears.

In accordance with the invention, it includes what is known as an active detector organ of the maximum high position of the bucket closest to the tower, this organ being connected to a scraping control logic element which, when the said organ is operated, on the one hand causes the immediate opening of a contactor stopping the winding of the scraping winch, and on the other hand causes the delayed closure of two contactors which respectively initiate winding of the return winch and unwinding of the scraping winch.

It can also have a material detection organ situated on the tower at the maximum level which the pile is to reach and, on the other hand, what is known as a stock detection organ, indicating when the bucket, during the scraping run, enters an intermediate zone, these two organs being connected to the scraping control logic element in such a way that it only acts when they are both operated and that in this case this logic element determines the delayed closure of the two above-mentioned contactors initiating the winding of the return winch and the unwinding of the scraping winch respectively.

The rotating platform connected to a motor and reduction gear unit can be rigidly connected to the mobile portion .of a rotation encoder co-operating with detector organs indicating the bunker over which the jib is situated and the wall to be passed over, these organs being connected to a rotation control logic element, but only bringing it into action when one of them is operated at the same time as the above-mentioned active detector organ or subsidiarily at the same time as the stock selector organ and the corresponding material detector organ subject to the scraping control logic element the rotation control logic element in this case causing the feeding of the motor and reduction gear unit in one direction or the other and for a limited period.

Various other features and advantages of the invention will also become apparent from the following detailed description.

Embodiments of the object of the invention are illustrated, as non-limiting examples, in the attached drawings.

In these drawings:

FIG. 1 is a diagrammatic elevation showing the dragline in accordance with the invention and its operating cycle in a bunker,

FIG. 2 is a perspective view showing a first embodiment of the dragline, with certain elements removed to clarify the illustration,

FIG. 3 is a view similar to FIG. 2 and relating to a second embodiment of the dragline,

FIG. 4 is a partial plan view of the position microswitches of the control apparatus of the dragline in accordance with FIG. 2,

FIG. 5 is an analytical diagram of the working connections made by means of this control apparatus,

FIGS. 6 to I 1 are simplified electrical diagrams defining the circuit elements of the control apparatus employed in accordance with the first embodiment,

FIGS. 12 and 13 are views similar to FIGS. 9 and 10 respectively showing modifications made to the said circuit elements in accordance with the second embodiment.

As clearly shown by FIGS. 1 and 2 or 3, and as is well known, the dragline comprises a pyramidal distribution tower 1, attached integrally to radial walls 2 defining bunkers between them for storage of various products (sand, fine gravels, pebbles, etc.). The walls end at the corners of the tower, on either side of the faces of the latter against which must be formed the piles of aggregate which can run through ports 3 formed at the bottom when the distributor hoods are open.

On the top of tower I is rotatably mounted a platform 4 having ajib 5 extending radially in cantilever manner over the bunkers. The jib is pivoted on the platform at one end and suspended close to its other end from an inclined stay 6, the latter being anchored at the top of a mast 7 rigidly connected to this platform.

By means of idling rollers 8, jib 5 supports a cable 9 known as a return cable fastened to the back, upper portion of a scraper bucket 10, preferably of the floating type with automatic filling. At its opposite end, return cable 9 is wound on the drum ll of a bucket return winch 12 carried by platform 4.

The back, lower portion of scraper bucket 10 is fastened to a cable 13 known as a scraper cable which, at its opposite end is wound on the drum 14 of a scraping winch 15 carried by platform 4.

Furthermore, in each bunker, the corresponding face of distribution tower 1 is provided with a material detector DM indicating when the maximum level of the pile has been reached in this position. Each material detector, which is of known type, consists of a deformable diaphragm which operates a microswitch when it is depressed by these materials.

The dragline also includes, to partially constitute the control apparatus in accordance with the invention, a collection of organs signalling that the bucket is passing through certain selected positions as it travels continuously in a closed cycle in vertical, radial planes, These organs are to allow the automatic and intelligent" op eration of the plant.

Of the above-mentioned position detector organs, the two embodiments (FIGS. 2 and 3) have in common a slack detector L and a rotation encoder CN arranged and organised in the same manner,

Slack detector L which is of known type, is mounted on jib 5 near rotating platform 4 to co-operate with return cable 9. It can consist of a lever 16 which can operate a microswitch l7 and is pivoted about a fixed axis 18 and connected to a spring 19 tending to apply an idling feeler roller 20, with which. the free end of this lever is provided, against cable 9.

The rotation encoder CN, which is also of known type, can have as many cams 21 as the distribution tower has bunkers. These cams are keyed on a shaft rigidly connected to platform 4, so that the position and angular opening of notch 22 of one of them corresponds to the bunker over which jib 5 extends at a given moment. Each cam co-operates with a microswitch 23, which therefore indicates, when it is operated, on the one hand the bunker in which bucket is working, and on the other hand the extreme positions of the jib relative to this bunker and from which surmounting of wall 2 must be effected. Microswitches 23 are designed to act on the supply ofa motor and reduction gear unit 108 (not shown in FIGS. 1 to 3, but marked in FIG, 11) rotating platform 4 in steps.

In the example mentioned above, rotation encoder CN is of the electromechanical type, but it is quite obvious that it could be of a different type, e.g. hydraulic, pneumatic, optical, etc..

The same is true of material detectors DM and slack detector L as the equivalent techniques cited above can lead to the required result for carrying out the invention.

Whether in the ease of the first embodiment of the dragline or the second, the control apparatus in accordance with the invention is designed to produce automatically and intelligently:

firstly, in each elementary bunker scraping zone, a

continuous, closed cycle of travel of bucket 10 indicated in FIG. 1 by a b 0 die, it being noted that the cycle comprises a lower scraping path a,b comprising generally horizontal movement inwardly toward the tower, a lifting path b,c adjacent the tower at the inner termination of the scraping path, a return path c,d from the upper termination of the lifting path outwardly toward the outer end of the jib and a lowering path d,e, a from the outer and termination of the return path to the outer end of the scraping path, it being noted that the distance of the lifting path from the tower can be varied in accordance with the amount of material in the bunker.

fore described below.

secondly, in each bunker, the angular shift by one step by rotation of platform 4 during the aerial return of the bucket,

lastly, surmounting of walls 2 without risk of interception of the bucket.

In accordance with the first embodiment illustrated by FIGS. 1 and 2 and 4 to 11, the above-mentioned control apparatus includes:

slack detector L,

material detectors DM,

rotation encoder CN; then it includes the following organs subject to moving cables 9 and 13:

a brake application" microswitch F,

a slack prevention microswitch I,

a surmount" microswitch S,

a back microswitch R,

a rotation authorisation microswitch AR,

a stock microswitch ST,

an active microswitch A,

safety microswitches SC; it also includes:

a programmer P,

a scraping cycle control logic element L,,

a rotation control logic element L lastly, it includes:

contactors C, and C controlling the supply of scraping winch l5: C, for winding the cable C for unwinding it contactors C and C, controlling the supply of return winch 12: C, for winding the cable C, for unwinding it contactors C and C, controlling the supply of motor and reduction gear unit 108: C, for rotation of platform 4 to the left C, for its rotation to the right a contactor C controlling a brake 24 co-opcrating with return winch l2.

Programmer P and logic elements L, and L are not described below in detail, given, on the one hand, that their construction and use are easily within the scope of the man of the art once the general program has been established and the particular program selected and, on the other hand that the active apparatus is prepared and constructed, which, furthermore, more particularly forms the object of the invention and is there- It is sufficient to know (FIG. 5) that interconnected logic elements L, and L are linked to programmer P for the latter to dictate to them the program to be carried out; at their inputs they receive information signals supplied by the above-mentioned organs F, R, SC, ST, A, L, AR, I, DM, S and CN; at their outputs, they deliver execution signals to contactors C, to C-,.

In this first embodiment of the control apparatus (FIGS. 2 and 4), microswitches F, I and S are fixed and controlled by a cam 25, this being mobile and its displacement being controlled by drum ll of return winch 12; in the example shown, cam 25 is guided in translation and rigidly attached to a nut cooperating with a turning screw 26, which is linked through a chain transmission 27 to drum 11.

In a similar manner, microswitches R, AR, ST and A are fixed and controlled by a cam 28, this being mobile and its displacement being controlled by drum 14 of scraping winch 15; in the example shown in FIG. 2,

cam 28 is guided in translation and rigidly attached to a nut cooperating with a turning screw 29, linked through a chain transmission 30 to drum 1.4.

This kinematic linkage is such that, when return cable 9 is wound and scraping cable 13 then unwinds, return cam 25 moves in the direction of arrow E(winding) to successively operate microswitches F, I and S and, simultaneously, scraping cam 28 moves in the opposite direction of arrow D (unwinding) to successively operate microswitches A, ST, AR and R.

It is important to note that microswitches F, I, S, A, ST, AR and R are positioned to correspond, as shown in FIG. 4, with the following points of the cycle shown in FIG. 1: between b and 0, between d and e, d,c,s, between 11 and s, between a and e. This positioning determines the chronology of the operation of the microswitches and, consequently, the speed or shape of the cycle. In this context, it is worth mentioning that portion a b c of the cycle is followed by bucket when the corresponding bunker is practically empty, which must obviously not happen. In reality, the bucket, drawn by scraper cable 13 as it is wound, takes as it passes the aggregates tipped by the lorries into the inlet of the bunker, as well as those in pile 31 distant from the tower 1 and, when it is full, ascends this pile, so that it follows a curve intermediate between portion a b c and line a c.

In the above, the geographical locations of microswitches L, DM and CN and then F,I,S,A,ST,AR and R have been specified. Locations of microswitches SC, which act in certain circumstances to temporarily interrupt the operation of the dragline, remain.

A first safety microswitch SC is positioned (FIG. 2) close to winch 12 under return cable 9 to act if the latter breaks.

A second safety microswitch SC is positioned (FIG. 2) close to scraping drum 14 so that i-s operating lever 32 can be acted on by the broken end of cable 13 when it turns; it therefore acts on breakage of scraping cable 13. 1

To facilitate understanding of the connections and the operation of the various organs composing the first embodiment of the control apparatus, the latter has not been shown in its entirity, as it would have been unintelligible and the corresponding description would not have allowed the essential features of the invention to be clearly revealed. On the contrary, FIGS. 6 to 11 show separately the circuits respectively enabling the elementary functions, as shown in FIG. 1 in particular, to be obtained.

In this particular illustration, the portion of logic elements L, and L: which is used has been shown diagrammatically for each circuit element, replacing it with an electromagnetic contactor, which can in fact be considered as a working equivalent. It must, however, be understood that this symbolic contactor is dependent upon the remainder of the logic elements which can consequently keep it in its state in accordance with the conditions required by programmer P.

Each circuit element includes at least one contactor. It is important to remember in the rest of the disclosure that contactors C, and C C and C C and C, are coupled in pairs and. that if one is closed, the other is generally open; moreover, bothof these coupled contactors can be opened by the logic elements.

The first circuit element of this first embodiment of the dragline control apparatus is the one shown in FIG. 6, by means of which the landing of the bucket at point a of the cycle (FIG. 1) is determined and scraping is then carried out along portion a b c of the cycle.

This circuit (FIG. 6) includes slack prevention microswitch I and the microswitch 17 of slack detector L mounted in series with a conductor 33, which can place switching voltage u across the excitation coils of contactors C, and C the mobile contacts 34 and 35 of which are connected to conductors 36 and 37 connecting scraping winch l5 and return winch 12 respectively to an electrical power source of voltage U. By virtue of its position (FIG. 4) microswitch I prevents any action of slack detector L, while the bucket is outside portion d, d, e, a, a of the cycle; when it is closed and the same is true of microswitch 17 as a result of the slackening of return cable 9, the coils of contactors C, and C are excited; under these circumstances, contact 34 closes, contact 51 of contactor C remains open, which has the effect of supplying winch 15 to cause the winding of scraping cable 13; at the same moment, or shortly before, contact 35 opens and that of contactor C remains open, so that winch 12 is not supplied and return cable 9 is free to unwind, except for a slight lateral braking of the corresponding drum 11.

When logic element L, has registered the signal of slack detector L, it keeps contact 34 closed, with the result that bucket 10 is drawn by scraping cable 13 to point e.

The second circuit element shown in FIG. 7, permits braking of return cable 9 slightly before the bucket reaches point c of the cycle (FIG. 1), scraping cable 13 continuing to be wound. This braking, at the end of the scraping run, has the effect, on the one hand, of lifting the rear portion of bucket 10 to empty it and, on the other hand, when a hole exists between the top of pile 31 and distribution tower l, of preventing the said bucket from falling sharply into this hole, which could damage the cables and the elements operated by them.

This circuit (FIG. 7) includes brake application" microswitch F, mounted in series on a conductor 38 which can place switching voltage u across the excitation coil of contactor C the mobile contact 39 of which is connected to a conductor 40 connecting brake 24 of return winch 12 to the power source of voltage U. It also includes a second, surmount microswitch S mounted in series on a conductor 41 which can take place switching voltage u across the excitation coil of On the other hand, when microswitch F is operated by return cam 25, i.e. just before point 0 of the cycle, it opens and cuts the supply of the excitation coil of contactor C,,; contact 39 opens in turn and the brake, being no longer supplied, is applied, which has the effect of stopping return cable 9.

With reference to this braking, it is interesting to note that return drum 11 can advantageously be designed like the one described in the French Patent Application filed on the same day by the applicant for: Drum for various winches."

This drum, as an extension of its helicoidal groove, has a spiral groove which, as its radius decreases, has the effect of reducing the drive torque and therefore the braking torque to be applied to cancel out the latter. In other words, if a hole exists between the top of the pile and the distribution tower, the bucket tends to fall and the braking is then particularly efficient to neutralize the shock effect which could be produced on the return cable resulting from the fall of the loaded bucket. 4

Moreover, projecting from its side disc and in tangential alignment with the end of the spiral groove, this drum has a pivot axis around which is mounted the terminal eye of the return cable; this pivot axis extends in parallel and fairly close to the geometrical axis of the drum; under these circumstances, when the return cable is completely unwound, it is aligned with the centre of the drum, and this drum then forms an efficient and solid stop for imperative halting of the bucket, which can prevent the latter from striking the walls if the operating cycle had developed a fault.

When return drum I1 is of the type described above, safety microswitch SC positioned close to winch 12 (FIG. 2) acts to prevent the return cable from winding in the opposite direction if it is aligned with the centre of the drum to form a stop.

The third circuit element (FIG. 8) enables bucket to be brought towards the end of jib 5, along an aerial path, between points 0 and d of the cycle (FIG. 1); this result must be obtained with cables 9 and 13 kept perfectly tensioned for the said bucket to follow a substantially elliptical path with a very small sag and thus manage to clear walls 2 without difficulty.

This circuit (FIG. 8) includes active microswitch A mounted in series on a conductor 44 which can apply switching voltage u across the excitation coil of contactor 45, shown in the drawing as equivalent to the portion of logic element L, to which this circuit relates; mobile contact 46 of this contactor 45 is itself mounted in series on a conductor 47, which can place switching voltage 14 across the excitation coil of a contactor 48, which is known as a delayed contactor, in that its mobile contact 49 closes with a delay I, when the said coil is supplied: mobile contact 49 is mounted in series on a bundle of conductors 50 which can place switching voltage 14 across the excitation coils of contactors C C and C the mobile contacts 51, 52 and 53 of which are connected to conductors 54, 55 and 56, connecting scraping winch 15, return winch l2 and return brake 24 respectively, to the power source of voltage u.

When active" microswitch A is closed by scraping cam 28, it firstly directs a signal to the portion of logic element L (not shown in the drawing) which has kept contact 34 of contactor C, closed up to now, the signal being designed to open this contact and thus stop the scraping winch.

At the same moment, active" microswitch A causes the closure of contact 46, which, in turn, causes the closure of contact 49 with a delay 2,. This latter contact triggers the closure of contacts 51 to 53 and, consequently and simultaneously, the release of brake 24, the winding of return cable 9 on winch l2 and the unwinding of scraping cable 13 from winch l5. Delay 1,

scent of bucket 10 at the inlets of the bunkers.

This fourth circuit (FIG. 9) includes the first surmount contact S mounted in series on a conductor 57 which can place switching voltage u across the excitation coil of contactor 58 shown in the drawing as equivalent to the portion of logic element L to which this circuit relates; mobile contact 59 of this contactor 58 is itself mounted in series on a conductor 60 which can place switching voltage u across the excitation coil of a contactor 61 with a delay t mobile contact 62 of the latter is mounted in series on a conductor 63 which can also place switching voltage 14 across the excitation coil of contactor C the mobile contact 64 of which is connected to a conductor 65 connecting return winch l2 to'the power source of voltage V.

This fourth circuit (FIG. 9) also includes back microswitch R mounted in series on a conductor 66 which can place switching voltage. u across the excitation coil of contactor C the mobile contact 67 of which is connected to a conductor 68 connecting scraping winch 15 to the power source of voltage V.

When the second surmount microswitch S is opened by return cam 25, it firstly informs the portion of logic element L, (not shown in the drawing), which has kept contact 52 of contactor C closed up to now, this information causing the opening of contact 52 and thus the stoppage-of return winch 12. In the same time, opening of surmount" microswitch S has the effect, as shown in FIG. 7, of causing the opening of contact 43 and cutting of the supply of brake 24, which locks return winch 12. At this moment, the bucket is at point d of the cycle (FIG. 1).

However, as scraping winch l5 continues to unwind cable 13, bucket 10 starts to describe a transitory, circular path centred on the end pulley of jib 5.

While the second surmount" microswitch S, which is normally closed, is opened by return cam 5 (FIG. 7), the first surmount microswitch S, which is normally open, is closed by this cam. From this moment, which substantially corresponds to the stoppage of the return cable, mobile contact 59 of logic element L, is closed, which causes the closure, with a delay of contact 64 of contactor C and thus the rotation of winch 12 to unwind the return cable.

Given that scraping winch 15 is still unwinding cable 13, while the return cable is also being unwound, bucket 10 follows portions d e of the cycle (FIG. 1).

However, when point e is reached, scraping cam 28 closes back microswitch R, which then'determines the opening of contact 67 of contactor C and thus the stoppage of scraping winch 15.

As too much of scraping cable 13 has been unwound, the bucket falls vertically along portion e a of the cycle (FIG. 1).

The cycle can be repeated under the influence of slack prevention" microswitch I and slack detector L, as described with reference to FIG. 6.

The fifth circuit element (FIG. 10) is designed to increase the volume of pile 31 close to distribution tower 1; in the proximity of point 0, corresponding to the tipping zone of bucket 10, this pile must not exceed a height limit, beyond which there would be a risk of the aggregates falling into the adjacent bunkers, this height being determined by the level of material detectors DM; therefore, once these detectors have been operated, to increase the stock, the bucket must be tipped in front of this point c for a sufficient period.

This fifth circuit (FIG. 10) includes stock microswitch ST mounted in series on conductor 69 which can place switching voltage u across the excitation coil of contactor 70, shown in the drawing as equivalent to the portion of logic element L, to which this circuit relates; it also includes material detector DM employed for the bunker being worked, this detector itself being mounted in series on a conductor 71, which can place switching voltage u across the excitation coil of a contactor 72; mobile contacts 73 and 74 of these contactors 70 and 72 are also mounted in series on a conductor 75, which can place switching voltage u across the excitation coil ofa contactor 76 with a delay I as is the case for the third circuit (FIG. 8); mobile contact 77 of this delayed contactor is mounted in series on a bundle of two conductors 78 and 79, which can place switching voltage u across the excitation coils of contactors C and C the mobile contacts 80 and 81 of which are connected to conductors 82 and 83, connecting scraping winch l5 and control winch 12 respectively to the power source of voltage V.

When the height limit of pile 31 has been reached, material detector DM is operated and mobile contact 74 closes. In the following cycle, when scraping cam 28 closes stock microswitch ST which, moreover, is positioned in front of active microswitch A, i.e. substantially adjacent to point s of the cycle (FIG. 1), this closure causes the excitation of delayed contactor 76, resulting, as for the third circuit (FIG. 8), in the unwinding of scraping cable 13 and the winding of return cable 9, without it being necessary on this occasion to release brake 24.

In these circumstances, bucket 10 tips its contents onto the pile behind point 0. Of course, supposing that this pile is not used, the stock cycle is limited in time" and is interrupted when the command for this is given by a timing device built into logic element L The sixth circuit element (FIG. 11) enables rotation of jib 5 to be obtained while the bucket is effecting its aerial return. For each bunker, the rotation is programmed stepwise so that scraping is effected, no matter whether to the right or the left, along contiguous radial strips covering the whole sector-shaped area of the bunker in question.

This circuit (FIG. 11) includes:

firstly, active" microswitch A mounted in series on a conductor 84 leading to mobile contact 23 of rotation encoder CN, which contact co-operates with the cam 21 associated with the bunker being scraped,

secondly, as in FIG. 10, the two contactors 70 and 72 of logic element L., the mobile contacts 73 and 74 of which are mounted in series on another conductor 75 leading to the above-mentioned mobile contact 23, it' being possible to place switching voltage u across the excitation coils of these contactors, by means of stock microswitch ST and respectively the material detector DM of the bunker being scraped.

Another conductor connects mobile contact 23 to the excitation coil of a contactor 86 shown in the drawing as equivalent to the portion of logic element L to which this circuit relates.

In these circumstances, if the dragline operates in normal cycle (FIG. 8) point e of the cycle is reached, active microswitch A places the coil of contactor 86 at switching voltage u. In the same way, if the dragline operates in a stock cycle (FIG. 10), stock microswitch ST and material detector DM place the coil of contactor 86 at switching voltage u, through contactors 70 and 72 of logic element L and when point s of the cycle has been reached.

Mobile contact 87 of contactor 86 is mounted in series on conductor 88, which can place switching voltage 14 across the excitation coil of a contactor 89 known as a time-lag contactor, in that if this coil is supplied, it immediately closes mobile contact 90, which opens automatically when a time-constant t, has elapsed; this time constant corresponds to the duration of rotation ofjib 5 necessary to cover one step.

Mobile contact 90 of time-lag contactor 89 is itself mounted in series on a conductor 91, which can place switching voltage 14 across the excitation coil of contactor C the mobile contact 92 of which connects a conductor 93 of the rotation motor and reduction gear unit 108 to the power source of voltage V.

When bucket 10 has carried out a normal scraping cycle (FIG. 8) or a stock scraping cycle (FIG. 10) and in as much as cam 21 of rotation encoder CN offers its'notch 22 opposite mobile contact 23, time-lag contactor 89 is excited and, while the said bucket is returning in the air to the bunker inlet (path 0 d), it causes the rotation of jib 5 for t;,; i.e., a period corresponding to the. step.

However, when one of the inclined ramps defining notch 22 of cam 21 causes the opening of mobile contact 23, the stepped rotation is interrupted.

It is specified above that this stepped rotation is determined by contactor C to the left. However, coverage ofa bunker or selection of another bunker can also be carried out to the right. The decision is taken by programmer P and can also be taken by the driver of the dragline. It is sufficient to know, from the practical point of view, that logic element L makes use either of the above-mentioned contactor C or of contactor C Furthermore, the logic elements determine the surmounting of walls 2 by bucket 10, as a function of the program applied to programmer P or of the order given by the driver. However, this determination is dependent upon rotation authorisation microswitch AR operated by scraping cam 28, on surmount microswitch S operated by return cam 25 and on microswitches 23 operated by cams 21 of rotation encoder CN, moved by platform 4.

In accordance with the second embodiment shown by FIGS. 1, 3, 13 and 14, the dragline control apparatus includes the majority of the elements defined with reference to the first embodiment, but with the difference that certain of them have different loca tions and that the electrical connections are adapted.

Thus, we again have (FIG. 3):

without changes: slack detector L, material detectors DM, rotation encoder CN and safety microswitches SC.

arranged directly dependent upon return cable 9: brake application microswitch F, surmount microswitch S and stock microswitch ST.

directly dependent upon scraping cable 13, active microswitch A.

Microswitches F, L, S and ST are mounted on jib and their operating rollers are situated in the passage of an elongate olive 94 rigidly attached to return cable 9.

Microswitch A is also mounted under jib 5 so that its operating roller is situated facing the free end of a lever 95, the opposite end of which is pivoted about an axis 96 rigidly attached to the mounting of this microswitch; lever 95 is arched concentrically with scraping drum l4 and has a longitudinal port 97 for passage of cable 13, the slope of which is essentially variable; lastly, scraping cable 13 is rigidly attached to a stop 98 positioned close to bucket 10.

In other words, in this second embodiment, instead of the microswitches being operated by cams translated by the winches as they rotate, they are operated directly by the cables; microswitches F, L, S and ST are, in fact, successively operated by olive 94 of return cable 9, while microswitch A is operated by lever95, directly receiving the pivoting impulse of stop 98 of scraping cable 13. Of course, it is essential that microswitches F, L, S, ST and A should be suitably positioned relatively to each other, as well as to olive 94 and stop 98, taking into account their respective distances from bucket 10, for the pulses which they deliver to correspond to the selected positions of the scraping cycle (FIG. 1) already defined with reference to the first embodiment.

In this second embodiment of the control apparatus are also found: logic elements L and L and contactors C] to C1.

The control circuit elements employing these various elements L, DM, CN, SC, F, S, ST, A, L L C to C of the second embodiment are organised and function in substantially the same manner as in the first embodiment, as shown in FIGS. 6 to 11.

Therefore, only the distinctive portions of the circuit elements of the second embodiment are shown in the drawings and described below.

The first circuit element is identical to the previous one in accordance with FIG. 6, except that slack prevention microswitch I has been removed.

The second circuit element is identical to the previous one in accordance with FIG. 7, except that instead of microswitches F and S being operated by return cam 25, they are triggered by the olive 94 of return cable 9.

The third circuit element is identical to the previous one in accordance with FIG. 8, except that instead of active" microswitch A being operated by scraping cam 28, it is triggered by lever 95 when this is pushed by stop 98 of scraping cable 13.

As brake 24 on return winch 12 can be removed in accordance with a simplified modification, the same applies in this case for thesecond circuit element and for contactor C of the third circuit element.

The fourth circuit element differs slightly from the previous one in accordance with FIG. 9, given that back" microswitchR no longer exists. It is shown in FIG. 12 and, as before, includes contactor 58 which represents logic element L, and excitation of which is determned by microswitch S when this is operated by olive 94 of return cable 9. In the same way, mobile contact 59 of contactor 58 controls the excitation:

not only of contactor 61 of delay t by conductor 60,

but also of a contactor 99 of time-lag t,, by a conductor 100.

Mobile contact 62 of delayed contactor 61 controls the excitation by conductor 63 of contactor C the mobile contact 64 of which controls the connection of return winch 12, by conductor 65, to the power source of voltage V, so that cable 9 unwinds.

Mobile contact 101 of time-lag contactor 99 controls the excitation, by conductor 102, of contactor C mobile contact 103 of which controls the connection of scraping winch 15, by conductor 104 to the power source of voltage V, for cable 13 to unwind.

In other words, when microswitch S is closed by olive 94 of return cable 9, it instantaneously causes the closure of contactor C for a period t,, so that scraping winch 15 remains supplied in the same direction and that the scraping cable continues to unwind for this period t.,; at the same moment, microswitch S causes the excitation of contactor 61, which only closes contactor C, after a delay 1 so that during this period return winch 12 remains stopped and from the end of this period t the said winch is supplied to unwind return cable 9. As a result, this second embodiment of the fourth circuit (FIG. 12) is equivalent to the first (FIG. 9), since time-lag contactor 99 enables the same result to be obtained as back microswitch R geographically shifted relative to surmount" microswitch S.

The fifth circuit element, shown in FIG. 13 differs from the previous one in accordance with FIG. 10 by the fact that the winch control delays are different, because of which the contents of bucket 10 can be tipped out without braking of return cable 9.

We again have material detector DM and stock microswitch ST which can excite contactors and 72 of logic element L this microswitch being controlled on thisoccasion by olive 94 of return cable 9. However, conductor 75, on which mobile contacts 73 and 74 are mounted in series is designed to place switching voltage u not only across the excitation coil of contactor 76 with delay t but also across that of a contactor 105 with a delay t mobile contact 77 of contactor 76 permits excitation by conductor 78 of contactor C mobile contact 80 of which controls the supply by conductor 82, at power voltage V, of winch 15 which unwinds scraping cable 13, while mobile contact 106 of contactor permits the independent excitation, byconductor 107, of contactor C the mobile contact 81 of which controls the supply, by conductor 83 at power voltage V, of winch 12 which winds return cable 9.

Thus the return cable pulls on the bucket before the scraping cable releases, so that the said bucket is emptied adjacent to point s of the cycle.

This modification is obviously applicable to the first embodiment (FIG. 10) when the return winch is not fitted with a brake.

The sixth circuit element is identical to the previous one in accordance with FIG. 11, except that stock microswitch ST is controlled by olive 94 of return cable 9 and that active microswitch A is triggered by lever 95, which is itself operated by stop 98 of scraping cable 13.

The invention is not limited to the embodiments of the object of the invention illustrated and described in the above, for various modifications can be made to them without departing from its scope.

The invention is applicable to a dragline which permits formation of piles, sufficiently supplied as a function of the requirements of a concrete manufacturing station, automatically and intelligently, against a distribution tower and in all the bunkers of the plant, with materials deposited at the inlets of these bunkers by lorries.

I claim:

1. An improved drag line system comprising a tower, radial walls extending from said tower to define separating bunkers, infeed ports provided at the bottom of said tower in each of said bunkers, a rotary platform mounted on an elevated portion of said tower, a cantilever jib mounted on said rotary platform, an idler roller at the outer end of said cantilever jib, a bucket return winch mounted on said rotary platform, a return cable wound on said bucket return winch and extending over said idler roller, a scraper bucket having said return cable fastened to a back portion thereof, a scraping winch on said platform, a scraping cable wound on said scraping winch and having its outer end connected to a front portion of said scraper bucket and control means for controlling said bucket return winch and said scraping winch for sequentially moving the bucket in a closed loop of travel in a vertical plane comprising a lower scraping path inwardly toward said tower, a lifting path upwardly adjacent the tower at the inner termination of the scraping path, a return path from the upper termination of the lifting path outwardly toward the outer end of said jib and a lowering path from the outer termination of the return path to the outer end of the scraping path, said control means including an active sensor means for detecting movement of the bucket to a position closely adjacent the tower by the scraping winch for immediately stopping the winding of the scraping winch and providing a time delayed initiation of operation of the winding of the return winch and unwinding of the scraping winch to initiate movement of said bucket along said return path.

2. The invention of claim 1 wherein said control means additionally includes brake actuating means including a brake application switch for initiating the application of a brake on the return winch in response to the sensing of the position of a bucket a small distance farther out from the tower than the position detected by said active sensor means.

3. The invention of claim 2 additionally including a material detector means in each bunker situated on the tower at the maximum level to which the material in each respective bunker is permitted to reach and a position detector means operable in conjunction with said material detector means for detecting positioning of the bucket during a scraping operation in an intermediate zone outwardly of said tower to initiate winding of the return winch and unwinding of the scraping winch for effecting upward lifting of the bucket over material in the bunker.

4. The invention of claim 3 wherein said control means includes means for initiating the winding of the return winch at a time slightly prior to the initiation of the unwinding of the scraping winch.

5. The invention of claim 4 wherein said control means includes means for maintaining said return cable in a taut condition as the bucket moves along said return path.

6. The invention of claim 5 wherein said control means includes means for controlling the return winch and the scraping winch as the bucket reaches a position approaching the outer end of said return path so that the bucket moves outwardly and downwardly following an inclined path to a position beneath the outer end of the jib followed by unwinding of the return winch to vertically lower the bucket to the outer end of the scraping path.

7. The invention of claim 6 wherein said control means includes means for indexing said jib through successive positions over one bunker solely when said bucket is moving along said return path to provide complete traversal of all parts of the bunker by the bucket.

8. The invention of claim 7 wherein said control means includes first and second movable actuator means respectively drivingly connected to said bracket return winch and said scraping winch so as to be positioned in accordance with the amount of cable on said winches at anygiven moment and switch means engageable by said actuator means for effecting the various control functions of said winches.

9. The invention of claim 7 wherein said control for effecting various control functions of said winches. l l l 

1. An improved drag line system comprising a tower, radial walls extending from said tower to define separating bunkers, infeed ports provided at the bottom of said tower in each of said bunkers, a rotary platform mounted on an elevated portion of said tower, a cantilever jib mounted on said rotary platform, an idler roller at the outer end of said cantilever jib, a bucket return winch mounted on said rotary platform, a return cable wound on said bucket return winch and extending over said idler roller, a scraper bucket having said return cable fastened to a back portion thereof, a scraping winch on said platform, a scraping cable wound on said scraping winch and having its outer end connected to a front portion of said scraper bucket and control means for controlling sAid bucket return winch and said scraping winch for sequentially moving the bucket in a closed loop of travel in a vertical plane comprising a lower scraping path inwardly toward said tower, a lifting path upwardly adjacent the tower at the inner termination of the scraping path, a return path from the upper termination of the lifting path outwardly toward the outer end of said jib and a lowering path from the outer termination of the return path to the outer end of the scraping path, said control means including an active sensor means for detecting movement of the bucket to a position closely adjacent the tower by the scraping winch for immediately stopping the winding of the scraping winch and providing a time delayed initiation of operation of the winding of the return winch and unwinding of the scraping winch to initiate movement of said bucket along said return path.
 2. The invention of claim 1 wherein said control means additionally includes brake actuating means including a brake application switch for initiating the application of a brake on the return winch in response to the sensing of the position of a bucket a small distance farther out from the tower than the position detected by said active sensor means.
 3. The invention of claim 2 additionally including a material detector means in each bunker situated on the tower at the maximum level to which the material in each respective bunker is permitted to reach and a position detector means operable in conjunction with said material detector means for detecting positioning of the bucket during a scraping operation in an intermediate zone outwardly of said tower to initiate winding of the return winch and unwinding of the scraping winch for effecting upward lifting of the bucket over material in the bunker.
 4. The invention of claim 3 wherein said control means includes means for initiating the winding of the return winch at a time slightly prior to the initiation of the unwinding of the scraping winch.
 5. The invention of claim 4 wherein said control means includes means for maintaining said return cable in a taut condition as the bucket moves along said return path.
 6. The invention of claim 5 wherein said control means includes means for controlling the return winch and the scraping winch as the bucket reaches a position approaching the outer end of said return path so that the bucket moves outwardly and downwardly following an inclined path to a position beneath the outer end of the jib followed by unwinding of the return winch to vertically lower the bucket to the outer end of the scraping path.
 7. The invention of claim 6 wherein said control means includes means for indexing said jib through successive positions over one bunker solely when said bucket is moving along said return path to provide complete traversal of all parts of the bunker by the bucket.
 8. The invention of claim 7 wherein said control means includes first and second movable actuator means respectively drivingly connected to said bracket return winch and said scraping winch so as to be positioned in accordance with the amount of cable on said winches at any given moment and switch means engageable by said actuator means for effecting the various control functions of said winches.
 9. The invention of claim 7 wherein said control means additionally includes switch actuators mounted on said return cable and said scraping cable for actuating switch means fixedly mounted adjacent said cables for effecting various control functions of said winches. 